Thank you for your question
My name is Clare
I shall do my best to help you but I need some further informtaion first
How old is your son and were you ever married to your ex?
What special financial needs does your ex think your son has?
How far along the spectrum is your son - what type pf school does he attend?
Do you pay spouse as well as child maintenance?
Was there actually a final financial order made within the divorce proceedings?
What happened to the Matrimonial home - and what income do you each have?
So her current home is rented (you refer to four bedrooms)
Your ex is incorrect.
The Court cannot deal with Child Maintenance unless both parties agree OR there is already a CMS (CSA) assessment in place and a top up is required.
Given what you have said there is in fact no reason why the diagnosis involves any extra expenses - especially since he does spend a fair number of nights with you.
She cannot claim any spouse maintenance and would have to justify any extra money sought for the child in terms of specific expenditure
I hope that this is of assistance - please ask if you need further details